Heat exchange apparatus



July 8, 1952 c s, MARTEL 2,602,648

HEAT EXCHANGE APPARATUS Filed May 18, 1949 2 SHEETS-SHEET 1 INVENTOR.CHARLES S. MARTEt A T TORNEYS J y 1952 c. s. MARTEL 2,602,648

HEAT EXCHANGE APPARATUS Filed May 18, 1949 2 SHEETS-SHEET 2- Fig. 5

INVENTOR. CHARLES S. MARTEL BY Q? ATTORNEYS Patented July 8, 1952 UNITED EP'ATE N T OF FliClE 2.602.643 :HEA'IiJEXCIlANGE APPARATUS Charless. 'Martel; JlVIedford; Mass), assignorw .StandardlThomsonCor-poration,;Boston,;Mass.,. 'azcorporatibnzofiDelawareAhlllibiatibnimaytm, 1949,,Serial No. 93,917

I The ipresentiinvention relates to 'heatexchange "apparatus and more,particularly to li'quid-to-liqcooler 'orp'at leastenables the use of asmall size of' such equipment wherebytthe aerodynamic difficulti'es: dueto introduction .of air athigh speed may be eliminated or'redu'ced.However the high pressures in both. the .fuel and oil.lines militateagainst the use of standard forms of heat ex-' :changc apparatus.

The object of the present invention is to provide a simple and readilyconstructed 'oil' cooler .capable of" efficient heat transfer" betweenliquid and liquid: andlcapable of withstanding high pressures.

To this end the principal feature of the pres ent invention comprises acellular construction inwhich the casing is of small cells, each" con-'stituting 'a single path for the .oil whereby the useiiof' longitudinalbafiie plates isavoided. Each 'CBllTlS. provided with a core of arelatively small bundle of tubes, the tubes being arranged longi-:tudina'lly'in each cell and in a proper association with the parts 'of'the cell toyprovid'e' for passage "of the; fuel through the'tubes.

In the preferred form the fuel is conveyed through the interior of thetubes and'the lubrieating oil is circulated outside. The tubes and thecasing are constructed to withstand the high pressures in both the fueland the oil systems. In its" preferred form" the cells are of extrudedaluminum and the tubestare' likewise of aluminum whereby the advantagesof ruggedness and light weight typified by the Woods Patent No.21292;,99'6 are obtained.

Other features of construction'iconsist of 'certain novel features ofconstruction"and'combinationsfand' arrangement of partshereinafterdescribed andparticularly defined in the claims.

In the accompanying drawings Fig. 1 is an end elevation of the preferred'form' of wheat exchange apparatus according to the present invention;Fig. 2 is a side elevation; Fig. 3' is a section .on line -3--3 of Fig.1 showing. the flows of oil and cooling fluid; Fig. 4.13 a perspectiveviewshowing the extruded sections of the shell; Fig. '5 is an elevationof a: tube bundle 01"iCDl6;

.Eig. 6 is an end elevation of the coresh wn i Fi'g. Fig. 7' is'a detailview' showing the core aluminum. Inview of the di'iiiculty of extrudingthe entire cooler in one'piece, the extrusion is preferably carried outin sections whereby the two end portions indicated generally at [-4 andit are each-extruded" with three cells, while the 'center'sectionlfi'has fourcells. The sections 'are'forme'd with welding flanges l9(Fig. 4) which are welded together as indicatedat 20 (Fig; 1') to formthe complete casing. As clearly'shown in the drawing, each cell isformed with bowed or arcuate outer'side walls to withstandinternal'pressures.

Received within each cell is a tube bundle indicated at '22. The'bundleformsa core of a relatively small number of tubes. For example, in aconstruction now in use each core-has at'tubes and the dimensions-ofthecell are approximately 1 4 inches across by 2 inches from side to side.

Each core comprises two tube sheets 24, 'the tubes 6, and theintermediate bafiles 28 to be referred to later. The tubes are ofextruded aluminum, preferably about /4 inch in outside diameter andhaving a wall thickness somewhat greater than is used in liquid-to-airheat exchangers; preferably the wall thickness is about 0.014 inch. Thetube sheets 24 are flat aluminum plates properly punched to receive thetub-es. The'intermediate bafflesZB are arranged to give a sinuous flowto the oil. Hence'each baillec'omprisesa punched section 29 to receivesomewhat more than half the tubes and an open section 30"throughwhich't'he' oil may pass in themanner indicated in Fig; 3'. Two baflles28" maybe used for each bundle, the two baflles being'reversedrelatively to each other, wherebythecirculating' oil is forced from'oneside of the bundle to the other in a sinuous fashion, so that itcontacts all of the tubes without channeling.

A core 22 is inserted into each cell, th-eitube sheets being of theproper shape to conform closely to "the walls of their own cellsyand'the core is positioned therein as shown in Fig. 3. Each core is retainedin its corresponding cell by "brazing a'sindicated'at'32; the brazingpreferably being carried out accordingflto th'eprocess described in theWoods Patent No: 23893175, dated November'20, 1945'.

Immediately inside the tube sheets the cells are provided with ports 33communicating with adjacent cells for passage of the oil from cell tocell. The oil is introduced in one end cell at 34 and flows in seriesthrough the cells to the outlet 35 in the cell at the opposite end.

Immediately beyond the tube sheets 24 are ports 31 for passage of theheat exchange medium through the tubes and cells. An inlet fitting 40spans the two cells shown in the upper right portion of Fig. 3, and anoutlet fitting 42 spans the two cells shown in the lower left corner ofFig. 3. These fittings are brazed or welded to the casing. The cells maybe closed by suitable flanges attached to opposite sides of the heatexchange apparatus, but preferably the cells are individually closed bycaps 44 shown in Figs. 3 and 8. Each cap is inserted into the end of itscorresponding cell and is suitably brazed or welded into position. Ifdesired the caps may be welded to the cells and this construction ispreferable because of the greater resistance to pressure.

In operation, fuel serving as the heat exchange medium is introduced at40 and removed at 42. The fuel may pass through the tubes of the severalcores in succession, but to reduce the pressure requirements, the flowis preferably through a series of parallel pairs of cores. Thus, asshown in Fig. 3 the fuel entering at 40 flows through two tube bundlesin parallel and is then directed into the next two bundles, and so on,until the last two bundles discharge it into the outlet 42. The ports 31are disposed so as to provide for parallel flow through adjacentbundles.

A thermostatic oil flow control valve 45 is secured to a pad 46 weldedon the casing adjacent the oil outlet 35. The valve is provided with anoil inlet 48 and an outlet 50. runs from the valve body to the oil inletopening 34. The oil flow is controlled by a thermostatic device shown inoutline at 52 in Fig. 2,'the construction of which may be of anysuitable form familiar to those skilled in the art whereby the oil maybe directed from the valve inlet 68 through '52 tothe casing inlet 34and thence around the tubes to the outlet 50, as indicated by the solidarrows in Fig. 2, or may be by-passed from 48 to 50 as indicated by thebroken arrow. When the oil is hot, it is circulated through theexchanger, but when its temperature falls below a certain point, it isby-passed from the cooler.

It will be observed that the general flows of liquids arecounter-current.

An important feature of the invention is the arrangement to Withstandhigh pressures. The pressures are relatively high, in some instancesbeing about 1,000 pounds per square inch for the fuel and about 300pounds per square inch for the oil. The tubes have a sufficient wallthickness to withstand the internal pressure. Furthermore, the system ishighly resistant to oil surges without the necessity of using asurgerelief valve as is customary in heat exchangers of the conventionaltype. The. small cellular construction resists bursting pressures of thecasing up to any surge pressures normally encountered. Furthermore, thesurges do not afiect the tubes since no crushing pressure is applied tothe tubes until the external pressure exceeds the internal pressure.Since surges of more than 1,000 pounds per square inch are not usuallyencountered, there is no tendency toward crushing of the tubes. Theavoidance of the A connection I surge-relief valve is important forreasons of reduced cost and improved reliability.

The arcuate arrangement of Fig. 1 is useful in some designs where theheat exchanger partly surrounds the jet engine or other equipment. Wheresuch an arrangement is not required the cells may be arranged in astraight pattern, either in a single row or in a plurality of rows, asindicated in Fig. 11, wherein an extruded casing 54 is formed with smallcells 56 having pressure-resisting curved outer walls 58, and internalpartitions, shown as straight longitudinal walls 60 and transverse walls52. The tube bundles or cores may be mounted as shown at 64. No flow.diagrams are given in Fig. 11, and the particular arrangements of theparts, fittings, closures, etc. are not shown, since they will, ingeneral, be similar to those previously described.

Although the invention has been described as embodied in an oil-to-fuelheat exchanger for aircraft, it'is not limited to such service but maybe appliedto any liquid-to-liquid exchanger, especially for operation athigh pressures.

Having thus described my invention, I claim:

1. A liquid-to-liquid heat exchanger for operation at high liquidpressures comprising an extruded shell having a plurality of smalltubular cells, each cell having a generally cylindrical exteriorsurface, the shell having unitary'partitions separating adjacent cells,a core for each cell comprising a bundle of straight tubes, each corehaving tube sheets at opposite ends, each tube sheet being of the sameshape as the crosssection of its corresponding shell, means for sealingthe tube sheets into the cells, inlet and outlet members connected todirect one liquid through the tubes, the partitions having ports outsidethe tube sheets on opposite sides to direct said liquid through thetubes and having ports between the tube sheets on opposite sides ofadjacent cells to direct the other liquid in a series of longitudinalpasses around the tubes in the several cells, and closures for the endsof the cells.

2. A liquid-to-liquid heat exchanger for operation at high liquidpressures comprising an extruded shell having a plurality of smalltubular cells, each cell having a generally cylindrical exteriorsurface, the shell having unitary partitions separating adjacent cells,a core for each cell comprising a bundle of straight tubes, each corehaving tube sheets at opposite ends, each tube sheet being of the sameshape as the crosssection .of its corresponding shell, means for sealingthe tube sheets into the cells, inlet and outlet members connected todirect one liquid through the tubes, the partitions having ports outsidethe tube sheets on opposite sides to direct said liquid through thetubes and havingports between the tube sheets on opposite sides ofadjacent cells to direct the other liquid in a series of longitudinalpasses around the tubes in the several cells, baille members mounted oneach bundle and having open portions extending partially across the tubespace to impart a sinuous path to said other liquid, and closures forthe ends of the cells.

3. A liquid-to-liquid heat exchanger for operation at high liquidpressures comprising an extruded shell having a plurality of smalltubular cells, each cell having a generally cylindrical exteriorsurface, the shell having unitary partitions separating adjacent cells,a core for each cell comprising a bundle of straight tubes, each corehaving tube sheets at opposite ends, each tube sheet being of the sameshape as the crosssection of its corresponding shell, means for sealingthe tube sheets into the cells, inlet and outlet members connected todirect one liquid through the tubes, the partitions having ports outsidethe tube sheets on opposite sides to direct said liquid through thetubes and having ports between the tube sheets on opposite sides ofadjacent cells to direct the other liquid in a series of longitudinalpasses around the tubes in the several cells, and individual closureswelded into the cells at the ends thereof.

4. A heat exchanger as defined in claim 1 wherein the cells are arrangedin a single arcuate row on an arc of large radius.

5. A heat exchanger as defined in claim 1 having a plurality of extrudedsections each section having a plurality of cells and provided with awelding flange, the sections being welded together,

6. A heat exchanger as defined in claim 1 in which the several cells arearranged in a plurality of rows with longitudinal and transverseinternal dividing walls.

CHARLES S. MARTEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

V UNITED STATES PATENTS Number

